The present disclosure relates to the collection of core samples and, more particularly, to cleaning and separating fluid and debris from collected core samples and core systems.
For many years, geologists in the oil and gas exploration industry have taken and analyzed rock samples of potential hydrocarbon-producing subterranean formations as part of their efforts to determine the profitability of completing wells from which the core samples are taken, as well as the desirability of further exploratory drilling in the same area. Once a formation of interest is reached in a drilled well, drillers often investigate the formation and the deposits therein by obtaining and analyzing such samples. Each representative sample is generally cored from the formation using a hollow coring bit, and the sample obtained using this method is generally referred to as a core sample.
Once the core sample has been transported to the surface, it may be analyzed to assess, among other purposes, the reservoir storage capacity (porosity), the flow potential (permeability) of the rock material that makes up the formation, the chemical and mineral composition of the mineral deposits residing in the pores of the formation, and the irreducible water content of the rock material. The information gleaned from analysis of the sample is used to design and implement well completion; that is, to selectively produce certain economically attractive treatment intervals from among those accessible by the well. Upon deciding on a well completion plan, all intervals except those specifically targeted for production are isolated from the target interval, and the deposits within the targeted interval are selectively produced through the well.
In a typical coring operation, an annular cutter called a coring head is deployed on the end of a tool string. The coring head is operable to remove an annular volume of material to create a core, which may then be captured and placed in a collection tube and subsequently retrieved to surface for analysis. In some coring applications, drilling fluid and debris within a wellbore (e.g., rock fragments from the wellbore wall) can fall into the core sample collection tube or chamber. This debris can contaminate the core sample, resulting in skewed testing results once received at the surface and analyzed. It also may cause the core collection chamber to become choked, which, among other things, may result in inability to obtain the requisite or maximum number of samples which may be recovered with a particular coring tool.